JPH0636491A - Magneto-optical disk device - Google Patents

Abstract

PURPOSE:To improve the recording density and to speed up a data transfer rate in the magneto-optical disk device. CONSTITUTION:A magnetic core is brought in extreme proximity to a recording film by slightly moving the magnetic core 2 by using a piezoelectric element 8 while maintaining the floating quantity of a floating magnetic head sufficiently large (at >=5mum) and monitoring the collision of a disk and the magnetic core 2 by an impact sensor constituted of the piezoelectric element 8. The impression of modulated magnetic fields is executed in this state. As a result, the danger of a head crash by dust, etc., is extremely decreased and the impression of the strong magnetic fields of sharp rising to the recording film is possible. The impression of the higher speed modulated magnetic fields is thus possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field modulation recording type magneto-optical disk device provided with a flying magnetic head as a magnetic head for generating a vertical magnetic field.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a floating state of a floating magnetic head used in a conventional magnetic field modulation type magneto-optical disk device. Reference numeral 1 denotes a slider, which exerts a force for pushing up the smooth surface 4, that is, a levitation force, by an air flow generated when the magneto-optical disk 5 rotates. A spring force of a suspension (not shown) exerts a force for pressing the slider against the disk, and the disk keeps a floating state at a position where the pressing force and the floating force are balanced. Such a slider 1 keeps a constant distance from the magneto-optical disk 5 by flying, and can always apply a stable modulation magnetic field without contacting the magneto-optical disk 5.

[0003]

The flying height of the flying magnetic head in the magnetic field modulation type magneto-optical disk apparatus using the above-mentioned conventional technique is set to 3 to 5 .mu.m, but the probability of a crash due to dust or the like is reduced. Therefore, as the flying height increases, the gap between the magneto-optical disk 5 and the magnetic core 2 increases, which makes it impossible to apply a sufficient modulating magnetic field.

When a higher-speed modulating magnetic field is applied, it is very effective to reduce the flying height (that is, reduce the distance between the magneto-optical disk 5 and the magnetic core 2), but a crash occurs. Considering the decrease in the reliability of the device due to the above, the distance between the magneto-optical disk 5 and the magnetic core 2 cannot be reduced. Even if the flying height is reduced to 1 μm, the thickness of the overcoat film 5a of the magneto-optical disk 5 is as thick as about 10 μm, and the magnetic core 2 and the recording film 5 are not formed.
The distance d is as large as 11 μm or more, and there is a drawback that a sufficient modulation magnetic field cannot be applied.

Further, due to some cause (for example, reduction of spring pressure of suspension, chipping of smooth surface 4, protrusion on disk, etc.), the flying height is decreased, and smooth surface 4 or magnetic core 2 causes magneto-optical disk 5 to move. However, even if it collided with, it could not be detected, causing a head crash.

Therefore, the present invention solves the above-mentioned conventional drawbacks, and an object thereof is to supply a flying head having a magnetic field application characteristic with higher reliability and higher performance than the conventional one.

[0007]

The magneto-optical disk apparatus of the present invention is characterized in that the magnetic head is a floating type and the magnetic core is fixed by a piezoelectric element fixed to a slider.

The magneto-optical disk device of the present invention is characterized in that the overcoat film of the magneto-optical disk is thinner than approximately 2 μm. In the magneto-optical disk device of the present invention, the device for driving the magnetic core of the magnetic head is When a voltage is applied to the piezoelectric element to finely move the magnetic core, a means for adjusting the amount of fine movement of the magnetic core by detecting the collision of the magnetic core and the magneto-optical disk using the same piezoelectric element is provided. Is characterized by.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a floating magnetic head according to the present invention. In the figure, 1 is a slider,
The magnetic core 2 is fixed to the end face via the piezoelectric element 8,
A modulation magnetic field is generated by applying a modulation current to a coil (not shown) wound around the magnetic core 2. The slider 1 has a smooth surface 4, and when the magneto-optical disk 5 rotates, an air flow flows into the smooth surface 4, so that buoyancy is generated. The magneto-optical disk 5 is composed of an overcoat film 5a, a reflection film 5b (film thickness of about 60 nm), a second protective film 5c (film thickness of about 100 nm), a recording film 5d, a first protective film 5e, and a transparent substrate 5f. . The thickness of the overcoat film 5a is usually about 10 μm, but in the present invention, it is 2 μm or less.

The flying height of the slider 1 depends on the area and shape of the smooth surface 4, the pressing spring pressure of a suspension (not shown),
Although determined by the linear velocity of the disk, the smooth surface 4 and the spring pressure are designed so that a sufficiently large flying height of about 5 μm can be obtained even at the innermost circumference where the linear velocity is the smallest and the flying height is the smallest.

The magnetic core 2 is fixed to the end of the piezoelectric element 8, and the tip of the magnetic core 2 is retracted by about 2 μm with respect to the smooth surface 4 when no voltage is applied. Therefore, when no voltage is applied, the magneto-optical disk 5
And the magnetic core 2 never come into contact with each other. As a result, the risk of head crash due to dust or the like can be greatly reduced. The piezoelectric element 8 has a structure in which an elastic shim 8b is sandwiched between two piezoelectric ceramic plates 8a (this structure is called a bimorph type), and is applied by applying a voltage between the elastic shim 8b and the piezoelectric ceramic plate 8a. A displacement that is almost proportional to the voltage occurs in the vertical direction. For example, if the length of the piezoelectric element 8 is 2 mm, it is about 10 when a voltage of 30 V is applied.
A displacement of μm is obtained. Therefore, the applied voltage is changed from 0V to 3
By changing to 0 V, the magnetic core 2 is
It is possible to project any length from 2 μm to +8 μm.

The piezoelectric element also has a property of generating a voltage when it is displaced, and an acoustic emission (sound caused by shock or vibration) generated when the magnetic core 2 contacts the magneto-optical disk 5 is generated. The piezoelectric element 8 can be used as a sensor for detecting (radiation of light).

Accordingly, the voltage applied to the piezoelectric element 8 is gradually increased while the slider is flying,
The applied voltage value when acoustic emission is first detected is, for example, 1.5 V (1 when the voltage of 30 V is applied.
Since a displacement of 0 μm occurs, 1.5 V corresponds to a displacement of 0.5 μm).
Can be located approximately 0.5 μm from the magneto-optical disk. Therefore, since the film thickness of the overcoat film 5a of the magneto-optical disk 5 is 2 μm or less, the distance between the magnetic core 2 and the recording film 5d is about 2.5 μm or less, and a sufficient modulation magnetic field can be applied. According to this embodiment,
The distance between the recording film 5d and the magnetic core 2 is 2.5 μm (the conventional 6
When it is reduced to one half, the modulation current of the magnetic coil required to obtain the same C / N as the conventional one was about 40 mA. This is about one fifth of the conventional modulation current. Further, the rise time of the modulation current is several nanoseconds, which is about one-third of that in the conventional case, and it was possible to apply a higher-speed modulation magnetic field.

The contact between the magneto-optical disk 5 and the magnetic core 2 is very weak, and the contact does not damage the surface of the magneto-optical disk 5 or damage the magnetic core 2. In order to avoid the risk of collision with the magneto-optical disk 5, a voltage is applied to the piezoelectric element 8 and the tip of the magnetic core 2 projects from the smooth surface 4 only when writing information that requires application of a magnetic field, and a magnetic field is applied. No voltage is applied at the time of reading or seeking that does not need to be performed, and the magnetic core has a smooth surface 4.
It is in a state of being retracted by about 2 μm.

FIG. 2 is a block diagram of the magnetic core fine movement device. A method of finely moving the magnetic core will be described below with reference to FIG. When the magneto-optical disk device writes information, the controller of the magneto-optical disk device (hereinafter referred to as ODD controller) 101 moves to the piezoelectric element controller 1.
A write command is issued to 02. The piezoelectric element controller 102 that has received the write command operates the piezoelectric element driver 10
3 is instructed to gradually increase the voltage applied to the piezoelectric element 8. Since the piezoelectric element driver 103 increases the voltage applied to the piezoelectric element 8, the displacement of the piezoelectric element 8 gradually increases and the tip of the magnetic core 2 gradually protrudes from the smooth surface 4.

When the magnetic core 2 is projected to a certain extent or more, the magnetic core 2 collides with the magneto-optical disk 5, causing acoustic emission. This acoustic emission is detected by the piezoelectric element 8 and the generation thereof is transmitted to the piezoelectric element controller 102. Then, the piezoelectric element controller 102 stops the instruction to increase the applied voltage and gives an instruction to apply a voltage 1.5 V smaller than the applied voltage at that time. The voltage value of 1.5v is 0.5μ
Since it corresponds to the displacement of m, the magnetic core 2
Can be kept at a distance of about 0.5 μm from the magneto-optical disk 5. Reference numeral 104 denotes a DC cut filter, which is applied to the piezoelectric element by the piezoelectric element driver 103.
This is for cutting the C voltage and transmitting only the AC voltage generated in the piezoelectric element 8 by acoustic emission to the piezoelectric element controller 102.

Further, since the linear velocity of the disk varies depending on the track position, the flying height varies depending on the track position. However, if the track position is known, the flying height can be known and the amount by which the magnetic core 2 should be finely moved can be determined. Therefore, as an operation method different from the above-described method, a table showing the relationship between the track position and the amount by which the magnetic core 2 should be finely moved is prepared in the piezoelectric element controller 102, and the piezoelectric element controller 102 causes the ODD controller 101 to operate. A method of instructing the amount of fine movement of the magnetic core 2 in accordance with the track position information received from

[0018]

As described above, when the flying head, the magnetic core fine movement device and the magneto-optical disk according to the present invention are used, the flying height of the flying magnetic head is sufficiently large (5 μm).
(m or more), keep the magnetic core very close to the recording film by finely moving the magnetic core using the piezoelectric element while monitoring the collision of the disk and magnetic core with the impact sensor composed of the piezoelectric element. You can Therefore, the risk of head crash due to dust or the like is extremely reduced, and a strong magnetic field with a sharp rise can be applied to the recording film, and a higher-speed modulation magnetic field can be applied. Therefore, there is an advantage that the recording density can be improved and the data transfer rate can be increased. Furthermore, by having the piezoelectric element perform both the role of finely moving the magnetic core and the role of a sensor for detecting a collision between the magnetic core and the disk,
Cost can be reduced because the structure is simple.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a floating magnetic head and a magneto-optical disk according to the present invention.

FIG. 2 is a block diagram of a magnetic core fine movement device of the present invention.

FIG. 3 is a cross-sectional view of a conventional floating magnetic head and a magneto-optical disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Slider 2 ... Magnetic core 4 ... Smooth surface 5 ... Magneto-optical disk 5a ... Overcoat film 5b ... Reflective film 5c ... Second protective film 5d ... Recording film 5e ... First protective film 5f Transparent substrate 8 Piezoelectric element 8a Piezoelectric ceramic plate 8b Elastic shim 101 ODD controller 102 Piezoelectric element controller 103 Piezoelectric element driver 104 DC cut filter

Claims (3)

[Claims] 1. A magneto-optical disk apparatus for recording information on a magneto-optical disk by irradiating a magneto-optical disk with a light beam and applying a magnetic field having a polarity according to a recording magnetic field by a magnetic head, wherein: A magneto-optical disk device, wherein a head is a floating type, and a magnetic core is fixed by a piezoelectric element fixed to a slider. 2. The magneto-optical disk device according to claim 1, wherein the overcoat film of the magneto-optical disk is thinner than approximately 2 μm. 3. When the device for driving the magnetic core of the magnetic head applies a voltage to the piezoelectric element to finely move the magnetic core, the same piezoelectric element is used for collision of the magnetic core and the magneto-optical disk. 2. The magneto-optical disk device according to claim 1, further comprising means for adjusting the amount of fine movement of the magnetic core by detecting it.